Mercury-vapor apparatus.



J. C. POLE.

MERCURY VAPOR APPARATUS.

APPLIUATION FILED s112125, 1912.

l l l @,645 Patented Sept. 15, 19141.

2 SHEBTSSHEBT 1.

J. C. POLE.

MERCURY VAPOR APPARATUS. APPLICATION PILPD sEP'T.5,-1912.

1,1 w. Patented sept. 15, 1914.

2 SHEETS-SHEET 2.

. inventan ai 7u@ UNITED sTATEs PATENT oEErcE.

JOSEPH C. POLE, OF NEW YORK, N. Y., ASSIGNOR T0 COOPER HEWITT ELECTRIC COMPANY, OF HOBOKEN, NEW JERSEY, A CORPORATION 0F NEW JERSEY.

MERCURY-VAPOR APPARATUS.

Specication of Letters Patent.

Patented Sept. '15, I9 I4.

Application filed September 5, 1912. Serial No. 718,652.

Y?) all lt1/0my it my concern.'

Be 1t known that I, JosErH C. POLE, a

subject of the Emperor of Austria-Hungary,

front elevations of a lamp to which my inand resident of New York, county of New York, State ot' New York, have invented certain new and useful Improvements in lVIercury-Vapor i\pparatus, of which the following is a specification.

1t is well known that in a mercury vapor lamp wherein the cathode and the anode are of mercury, the difference in heat produced bv the unequal drop of potential on the two electrodes generally causes a distilling of mercury from one electrode to the other so that, in order to keep a lamp of that type continuously running Without one electrode being emptied out, means have to be provided for continuously or intermittently replenishing the .mercury of that particular electrode which has the tendency to empty out. The tubes of lamps of this class are frequently bent into the general shape of an inverted U, the mercury electrodes being located at the bottom of the` legs of the yoke and the upper part oi.' the yoke constituting the light giving portion when the lamp is in operation. Such lamps, especially those operating at low current (about one ampere) sometimes incline, in the operating lamp, to periodical fluctuations of the mercury in the two legs of the tube. T hese fluctuations may cause considerable variations of the eurrent,-so great at times, as to cause the lamp to be extinguished. Another difficulty with lamps of this type is due to the danger of fracture during' tansportation which danger is especially great in connection with certain types of so-callcd quartz lamps, wherein the lamps operate at atmospheric pressure. A considerable amount of attention has been given to the starting,r of lamps of this class where the current is first passed through a continuous body of mercury in a tube and means have to be provided for caus ing a. separation of the mercury and the formation of an initial small arc which afterward extends or propagates itself in the manner now well recognized. I have devised means whereby the various desirable operations above referred to may be accomplished in a simple manner and whereby the difficulties mentioned may be Overcome, also 'by simple means.

The details of my invention will be understood by reference to the accompanying drawvmgs 1n wh1chliigurcs l and 2 are respectively side. and

yention is applied, portions of the lamp bcing broken away to show details; Fig. 3 is a. front elevation of the same lamp illustrat ing more particularly electric circuits which may be used in connectiontherewith; Fig. 4 is a side elevation of a modified form ot' lamp apparatus, showing also in section a portion of the lamp to which my means for protecting the lamp during transportation are applied; Fig. is a front elevation ot' the same lamp, sectioned at the top to show my improved means for causing the initial arc for starting the lamp.

ln Figs. 1, 2 and 3, 1 is the luminous part o'f the lamp, the same being;l bent in the form of an oval with two upright legs, 2 and 3, one at each side of the bentportitm ot the tube. At the lowerends ot the legs are curved tubes 4 and 5 extending in opposite directions and terminating, one in an upright enlargement G and the other in a Similar enlargel'nent, 7. These enlargements connect with each other by means of a, narrow tube, 8, provided at- 9 and 10 with still narrower contracted portions, as clearly shown in Figs. 1 and Depending from the center, or approximately the center, ot the curve of the tube, 1, is a teat, 11, filled with mercury, and above the teat, approximately, but prefcn ably not quite, at the summit of the luminous tube, is a contraction, 12. The said teat is supplied with an electric healing),v spiral, 13, the connections of which appear in Fig'. 3, where. 14; and 15 are the leads oi the source of direct current supply. and 1.6 and 17 constitute with the terminals 18 and 19- a double pole switch. Beyond the switch a circuit passes by way of an inductance coil .20 and an auxiliary conductor, 21, to one end of the heating spiral, 13, from the other end. of which it travels by way of the conductor 22 into connection with a conductor, Q3, constituting one of the main leading-in wires of the lamp\ The other main leadingdn u ire, 24, is connected by a lead, 25, through -1 series resistance, 26. to the other pole of the supply. lAn auxiliary leadingsin wire, 37. is connected by a branch.. 28, to'the lead.l 2l. Returning to the physical construction of the lamp of Figs. 1, 2 and 3, it will be noted that the bent tubes 4 and 5, at the bottom of the structure, are provided at 29 and 30 with contractions, as shown. These contractions ha ve a very small inside diameter, thus constrictng the opening between the legs 2 and 3 of the tube and the enlargements, Gand 7. Attention may further be called to the fact that the main leading-in wires, 23 and 24, are surrounded, where they pass down the enlargements 6 and 7 with small insulating tubes, 31 and 32. It may also be noted that the. normal mercury level in a cold tube, as shown at 33, is below the point reached by the end of the auxiliary leading-in wire, 27. That is to say, when the lamp is not in operation the auxiliary wire, 27, does not touch the surface of the mercury.

The operation of the lamp is the following: A certain direct current voltage, say 220 volts, being applied to the supply con ductors, 14 and 15, and the double pole switch, 16, 17, 18 and 19, being closed, an electric current. will first pass through the coil 20, the spiral 13, the leading-in wire 23,l

and the mercury in the tube 1 the mercury in which then fills the whole luminous tube, to the other leading-in wire, 24, whence it passes through the resistance, 26, back to the supply. The mercury in the teat, 11, being heated by the spiral, will vaporize, and the vapor bubbles, rising, will separate the mercury in the contraction 12, and the contact of the mercury in the luminous tube being interrupted, Aa small are will be formed. The heat of the initialarc will increase the vapor pressure and ultimately drive the mercury from the luminous tube into the enlargements 6 and 7, until a certain equilibrium between the inside mercury vapor pressure and the outside atmosphere isreached and the mercury settles, for example, at levels 35-36 and 37--38.

The height of the mercury levels depends wholly, in a given case, upon the voltage applied to the lamp and upon the cooling surfaces of the lamp. When equilibrium in an operating lamp is reached, the mercury in the enlargement, 6, makes contact with the auxiliary leading-in wire, 27, thus short circuiting the heating coil, 13, and stopping its operation during the time the lamp' is under current.

The cooling is increased and varied by heat radiating ribs, 39, of sheet metal mounted on the enlargements, 6 and 7, as

shown, for example, at the left in Fig. 4.

The function ofthe tube, 8, no w becomes clear. When, for example, in my lamp, the positive pole of the supply is connected to the mercuryI in the enlargement, 6, the mercury level in this enlargement will generally drop and the enlargement, 7, will get filled up. This, however, will roceed only until 55 the mercury level, 38, ig. 3) in the enlargement, 7 reaches the connecting tube, 8, when the mercury will enter into this tube and fiow through it back to the enlargement, G. To prevent the mercury from flowing too rapidly from one enlargement to the other, I provide one or more narrow contractions as 9-10, in the connecting tube; and to prevent short circuiting'between the leading-in wires, the connecting tubes, I protect said leadingin wires by the small insulating tubes, 31 32, already described.

The enlargements Gand 7 are of equal volume, and either 'one is so large that, whenv the mercury fills one enlargement up to the connectingtube, 8, the other enlargement is not completely emptied out and still mamtains safe electrical contact between the leading-in wire and the mercury. It is to be understood that the emptying out of one enlargement and the filling up of the -other occurs very slowly, and the mercury does not generally flow continuously through the tube 8, but goes over in small drops and at certain intervals of time. It will also readily be seen that such a lamp is not only self regulating but is also independent of the maintenance of aA fixed polarity, since it is perfectly symmetrical.

The described contractions 29 and 30 in the tubes 4 and 5 are provided in order to lessen the fluctuations of the mercury to a degree where they are no longer troublesome. These contractions have preferably so small an inside diameter that they allow the mercury to pass but very slowly into or out of the luminous tube. In the absence of some provision of this sort, -the periodical fluctuations of the mercury in the two legs of the luminous tube cause variations,

of current which, in some instances, might result in the extinguishment of the lamp.

I have found it sometimes convenient and advantageous to replace the starting teat, 11, by a small upright tube, 40, formed on the top of the luminous tube 1, as shown in Figs. 4 and 5. The heating spiral appears at 41 and may be connected in the circuit in a way similar to that of the spiral 13 described above. A small air bubble, 42, is left in the trap or, as a rule, forms of itself after the lamp has been in use for some time. The mercury thus reaches only as far as the level, 43, filling, of course, the whole luminous tube, as before. l WVhen the current is applied to thev lamp, the'heater 41 will cause. the air bubble 42 to expand, drive the mercury out of the trap, and finally interrupt the contact with the mercury in the contraction, 44, of the luminous tube. This contraction like that heretofore described, is preferably placed a little off the middle of the tube. The advantage vof this method of starting is that it provides a small trap for gases which, in small 22 24, by the mercury flowinfr through l and their valves.

time gives vto the liberated gases a positivefunction. The gases can always get out of the way and into the trap, 'instead of being liable to impede the starting of the lamp.

For reducing the liability of fracture or derangement of atmospheric mercury lamps during transportation, I provide at the points of juncture between the tube' 4 and the enlargement 6 on the one hand and the tube 5 and the enlargement 7 on the other hand, valve seats and 46 adapted to receive valves 47 and 48 respectively.. The

valves and valve seats are conical in shape and the valves are ground into the seats so as to form regular ground joints. The valve stems 49 and 50 are pushed tightly downward by means of springs, one of which is shown at 51, as being held under a small cap, 52, covering`the upper end of a tubular extension, 58, of the enlargement, 7. The valves and valve stems are preferably of iron and they serve only during transportation and may be removed after the lamp is installed,-simply by taking oil" the caps 52 and pulling out the rod or stems vprovided with constrictions.

2. In a mercury vapor lamp comprising a luminous tube, a leg on either side thereof, an enlargement on each leg, and mercury l in said luminous tube and partly filling the enlargements, the enlargements being joined to the main luminous tube by connecting tubes terminating at the top in conical' seats for valves, all in combination with vrods of iron or other suitable metal adapted to serve as valves forsaid seats.

3. In a mercury vapor lamp comprising a luminous tube, a legon either side thereof, f

an enlargement on each leg, and mercury in said luminous tube and partly filling the enlargements, the enlargements being joined to the main luminous tube by connecting tubes terminating at the top in conical seats for valves, all in combination with rods of iron or other\ suitable metal adapted Ito serve as valves for said seats, and capable of forming ground joints therewith.

4. In a mercury vapor lamp comprising a luminous tube, a leg on either side thereof, an enlargement -on each leg, and mercury in said luminous tube and partly lling the enlargements, the enlargements being joined to the main luminous tube l by connecting tubes terminating at the top in conical seats for valves, all in combination with rods of iron or other suitable' metal adapted to serve .I

lfor valves, all in combination with rods of iron or other suitable metal adapted to serve as valves for said seats, and detachable means for holding the rods to their seats.

Signed at New York, in the county of New York, and State of New York, this 28th day of August,A. D. 1912.

JOSEPH C. POLE.

Witnesses: l

HAROLD B. Woonwann, PERCY H. THOMAS. 

